Lyft pairs one passenger (or equivalently, one party) to one driver. We've built a system which will actually take your route into consideration, and pair you with additional passengers that are en-route (relative to you). In other words, your ride is shared with other people heading in the same direction you are.

While are drivers are for-hire at this phase (in order to provide a reliable and available supply-side), there is much higher utilization in the car as multiple riding parties are paired to it.

EDIT:

I see the question was changed slightly. Higher utilization makes all the difference. Our current public transit system is just as you've stated: a vehicle being shared by "more strangers" (in your own words). We envision our system creating a completely adaptive and dynamic transit grid, which lends itself to predominant way in which people get around in the future.

It looks like you'd be splitting the ride with others so filling up more of the car and thus paying less. Perhaps even meeting others. Sounds like enough of a difference to me.